Pulverized-fuel-burning furnace



i Patented ct. 7, i924..

l i If;

HENRY KREISINGER, F PITTSBURGH, PENNSYLVANIA,

assrenoa 'ro ooMBUsTIoN iii PULVERIZED-FUEL-BURNING FURNACE.

Application filed December 13, 1920. Serial No, 430,224.

To all whom it may concern.'

Be it known that I, HENRY KREISINGER, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and 5 State of Pennsylvania, have invented. certain fractories may be kept below the melting temperature of the ash in the coal. v

A further object is to admit the air used to cool the walls of the combustion chamber into the combustion chamber for completing the combustion of the fuel which is advantageous for the reason that such air is thus preheated and therefore returns to the furnace heat lost by radiationv iL e., heat is taken away at the points where-it would do damage and is returned toppoinfts `where it aids both ignition and combustion of the coal. i y

Another object of the invention is to provide a simple arrangement for controlling the supply of the preheated air to the furnace. Still another object is to admit combustion air in such manner as tol advantageously further admixture of the fuel therewith and to thereby promote better combustion. The foregoing,

objects as may hereinafter appear, b lliystrated in preferred form in the accompanying drawings, wherein: Fig. 1 is a partial front elevation of a furnace embodying my improvements; Fig. 2 is a section taken on the line 2--2 of Fig. 1; and Fig. 3 is a longitudinal section through thef furnace shown in Fig. 1.

Referring now to Figs. l, 2 and 3, the furnace comprises a combustion chamber A to which the fuel or a mixture of fuel and air is supplied, preferably from the top in a vertically downward direction by means of the burners 7, the point of inlet being adjacent the front wall 8 of the combustion chamber. The outlet 9 from the combustion chamber is also preferably located in the upper part thereof so that the fuel and flame together with such other I obtain will take a substantially U-shaped course in means of. a construction which I have ilthe combustion chamber. Over the outlet 9 any suitable boiler, such as water tube boiler BQgis located.

The burners shown and described in my copending .application Serial No. 418,640, filed Oct. 22, 1920 now Patent #1,463,283, and they are preferably constructed so as to supply a mixture of fuel and air. The additional air required for combustion purposesis supplied. preferably by induction, through the front wall at pointsbelow the inlet in a manner now to be described. 4

Formed in the walls of and extending around the combustion chamber are a plurality of ducts 10. Air is supplied to each d uct by means of a pipe 11 which may be open to the atmosphere or connected to forced draft ducts. These pipes 11 are secured to the rear wall of the combustion chamber, over aper- 7 are of the constructioni tures or ports 12 opening into the ducts 10.

Each pipe 11 is independently controlled by suitable damper mechanism 13 as diagrammatically illustrated in Fig.v 2. A plurality of openings or ports 14 formed in the front wall 8 of the combustion chamber constitute the outlets for discharge of the air from the ducts or compartments -10 to the/combustion chamber. In the drawings, Ihave illustrated a row of iive of such ports i4 from each duct 10 in the front wall, but it will be understood that any desired number may be employed. A plurality of peep holes 15 are also provided at various points so that the condition of the fire may be observed, Such peep holes being shown, the ducts 10 extend substantially horizontally, each from its .air vsupply o ening 12 to its air discharge 14 at substantlally the same level. l'

It will be seen from theV foregoing that the arrangement is such. that' the au' admitted through the pipes 11 in traversing the ducts will absorb heat from the walls, so that in eifect the furnace is an air cooled one in which the temperature of the furnace walls is kept below the melt-ing temperature of the,I ash in the coa-l. As a result, the slag or slag-like deposit which athers on the walls of the combustion cham er during operation, is cooled below the fusion point '90 covered by plates 16 of :colored glass or other'suitable material'. As

and forms a skin protecting the surfaces .cooled wall is no longer suicient to solidify the deposit. This preheated air when introduced into the furnace aids both ignition `and combustion of the coal and tends to increase eiiiciency. llt will also bel seen that the use of the cooling air as the additional air needed for completing combustion sets up a very simple but effective cooling system which automatically responds tov operating conditions.

lt will also be noted that the control of v the air supply for each duct by damper mechanism located in the inlet pi l1, is preferable to supplying an in ependent damper for each port 14. Any one or more of the ducts may thus be completely cut ed or adjusted to any desired degree.

No claim is specifically made herein to the water screen C, whereby a cooling zone for preventing coalesce-nce of falling ash into a fused mass is maintained in the lower portion of the combustion chamber, this being the subject matter of the aforesaid application.

lt will be observed that the air flows from both ends of the ducts toward the middle thereof and that the inlets from the ducts to the chamber are located intermediate the ends of the ducts. This is highly advantageous for experience shows it produces a better mixture of the central portion of the fuel and flame stream with the air, a region where effective admixing is difiicult. This is due either to the fact that the air entering at the inlets in the middle portion of the wall has a higher velocity or to the fact that more air enters through the middle inlets, because the oppositel moving stre-ams of air in the wall meet at t e middle thereof. There are no inlets in the side and rear walls whereby clogging would result from tangential discharge of molten refuse particles from the flame stream. The cont-rol of the How of air throughA each compartment affords control of combustion and of cooling.

-There is an important' relation between the preheating of the combustion air and the cooling water screen. The cooling zone has been created by admitting relatively cold air into the combustion chamber beneath the fuel and flame stream. but when combustion air is drawn through ducts in the chamber wall for preheating purposes, the resistance to the flow of air is such that too much cold air would be drawn `into the bottom of the combustion chamber and not enough air for combustion would be drawn through the ducts. Thus combustion itself is interfered with and if the supply of cool ing air' is cut oil' to overcome this difiiculty, then the furnace temperature rises and produees slagging. Hence some other means than cooling air for the prevention of slagging must be employed. The water screen serves this purpose.

iiaeaa T claim:

l. ln combination, a combustion chamber for burning finely divided fuel in suspension having a hollow wall divided into a plu rality of vertically spaced substantially horizontal compartments, means whereby air is admitted to the compartments at one side of the chamber, each compartment having a plurality of delivery openings into the chambcr at the opposite side thereof, and means for admitting finely divided, fuel into the chamber in a downward direction adjacent the wall atthe` said opposite side of the chamber.

2. lfn combination, a combustion chamber for burning finely divided fuel in suspension having a hollow wall divided into a plurality of vertically spaced substantially horizontal compartments, means whereby air is admitted to the compartments at one side of the chamber, each compartment having a plurality of delivery openings into the chamber at the opposite side thereof. and means for 'admitting finely divided fuel into the chamber in a downward direction adjacent the wall at the said opposite side of the chamber. together with means for controlling the flow through each compartment.

3. Tn combination, a combustion chamber for burning finely divided fuel in suspension having an outlet in an upper part thereof and having means for admitting finely divided fuel in a downward direction into the chamber adjacent one side of the chamber, the wall surrounding said chamber being hollow and divided into a plurality of vertically spaced substantially horizontal compartments provided vwith air admission means thereinto at a point remote from the region of the entering fuel and with air delivery openings therefrom into the chamber near the region where the fuel is introduced.

a. ln combination. a combustion chamber having an outlet in an upper part thereof, means for admitting finely divided fuel in an upper part thereof in a downward direction whereby the fuel and flame stream reveits in lll-form, the wall surrounding said chamber being hollow with inlets from the space therein into the chamber adjacent the entering fuel and with means for admitting` air from the exterior into the space within thewall at a point removed from said inlets` said wall being otherwise imperforate in regions where refuse particles leave the flame and travel toward the wall.

5. ln combination, a combustion chamber having an outlet in an upper part thereof,` means for admitting finely divided fuel into the chamber in a direction out of line-with the outlet whereby the fuel and flame stream curves toward the outlet in its traverse, the upright wall surrounding said chamber being hollow for the traverse therethrough liti of combustion supporting air and being provided with delivery openings into the chamber in the region of the igniting fuel, said wall being substantially imperforate in those portions adjacent the region of the bend in the fuel and fiame stream. said chamber being of a size such that combustion is suhstantialigY completed therein.

6. In combination, a combustion chamber for burning finely divided fuel in suspension having a hollow upright Wall divided into a plurality of vertically spaced substantially horizontal compartments into which and through which air for combustion fiows, the compartments having inlet openings into the chamber, means for controlling the flow through each compartment, and means for admitting finely divided fuel into the chamber in a downward direction adjacent that portion of the wall where the combustion air enters into the chamber.

7. in combination, a combustion chamber having an outlet in an upper part, means for admitting finely divided fuel in an upper part thereof in a downward direction, means for successively supplying preheated combustion air into the chamber at a plurality of levels, and a water cooled screen located between the zone of combustion and a chamber defining surface for creating a cool zone between the Haine and such surface through which refuse particles passing from, the flame in regular operation to suoli surface are cooled in transit below slag forming temperature. Y

8. In combination. a combustion chamber for burning finely divided fuel in suspension having a hollow wall through which air for combustion flows. said wallhaving a plurality of spaced air delivery openings into the chamber, and said wall also having air admission means thereinto providing a flow of air within the wall in twoy opposing streams each flowing toward the region in which the delivery openings are located, and

means for admitting finely divided fuel intoI the chamber in a downward direction adjacent that portion of the wall having the delivery openings. Y

In testimony whereof, I h ave hereunto signed mynarne.

HENRY KREISINGER. 

